When it comes to automation, one of the goals in industry is to get rid of safety fencing. It is inflexible and takes up a lot of space. When safety fencing is eliminated, many people immediately think of small, lightweight robots that move cautiously and cannot carry heavy loads. But does that necessarily have to be so when humans and robots share a common workspace? In conversation with Christian Tarragona, Senior Vice President at KUKA Research and Development.
Christian Tarragona: We are seeing a trend in which those who had not previously considered automation are showing increasing interest in the topic. Their top priority is to be able to quickly and, more than anything, easily automate individual work steps in their production. As soon as they have to start thinking about safety fencing, most of them opt out. And this is precisely where human-robot collaboration (HRC) comes into play. HRC is instrumental in helping to make automation easy. The safety fence is eliminated and you can simply show the robot what it has to do – without a major programming effort. First and foremost, the objective is therefore to automate a task previously performed manually. Only in a second step is thought given to how the human and the robot are to share the same workspace.
So HRC doesn’t always have to stand for “human-robot collaboration”, but rather could also refer to “human-robot coexistence” in many applications?
Christian Tarragona: Exactly. Or even human-robot cooperation. There are, so to speak, different levels. With coexistence, the human and the robot work next to each other, the workspaces do not overlap and the concept does not provide for contact with the robot. With cooperation, the human and the robot share a common workspace, but do not work hand in hand during each work step. Instead, there is a defined intervention zone in which the robot throttles down its speed as soon as the human enters. With collaboration, the human and the robot work in a shared workspace. Contact between the two is permitted and the velocity is adapted here too so that safety is ensured at all times.
And this involves exclusively small, sensitive robots with a low payload capacity?
Christian Tarragona: No. There are projects in the field of HRC which quite deliberately incorporate larger industrial robots. Projects of this nature are of particular interest for areas which have been only partially automated so far. One example is final assembly in the automotive industry. The processes here still have a very high manual content. On a flow production basis, the seats are installed, the cockpit is inserted, the roof liner is fitted and the wheels are mounted. Integrating robots into this manual production line would result in the pure coexistence of man and machine. The work steps are clearly divided between humans and robots, but safety fencing cannot be installed on such a line since – on account of the continuous production – the robot workspace is not static, but rather must adapt to the flow of the line. The same applies to the workspace of the human operators. This occasionally leads to the workspaces overlapping.
And what would you say are the advantages and disadvantages of collaboration and coexistence?
Christian Tarragona: If robots and humans work without a safety fence and next to each other in separate workspaces, it is possible to increase the velocity of the robot. That boosts the efficiency. In this case, different parameters are set than those used for collaboration. To change from a work environment of coexistence to collaboration, a certain effort is required. Here, the safety sensor equipment is the key criterion that makes the difference. The goal is for a safety maintenance technician to take no more than half an hour for such a changeover. In general, however, the aim is for humans to be supported in their work by intelligent systems. Humans and robots work together, perfectly complementing each other with their respective skills. With collaboration, it’s not just about safety fencing, but rather the added value that results from the operator working in direct collaboration with the robot. This makes particular sense wherever direct human-robot collaboration leads to added value. This has the following advantages: simplified automation, consolidation of space, feeding material without interrupting system operation, improved accessibility, more flexible cell concepts, programming by demonstration, and the appropriate division of labor with the cognitive tasks carried out by humans and the repetitive tasks performed by robots. Depending on a range of factors such as cycle time, batch size, availability of personnel, and above all the processes concerned, tomorrow’s automated production stations will be designed accordingly. This can range from a purely manual assembly station right up to a fully automated welding station. Between these two extremes, HRC solutions can be implemented on a scalable basis.